As people set their clocks forward an hour for daylight saving time this Sunday (March 8), they may also want to take extra care of their heart. That's because people tend to have more heart attacks on the Monday following spring's daylight saving time, according to a recent study.
In fact, the number of heart attacks increased 24 percent on the Monday following a daylight saving time, compared with the daily average for the weeks surrounding the start of daylight saving time, according to a 2014 study in the journal Open Heart.
With this in mind, people who are at risk of a heart attack — such as those who smoke, have a strong family history of heart attack or have high cholesterol or high blood pressure — shouldn't delay a trip to the emergency room if they feel chest pain, said senior researcher Dr. Hitinder Gurm, an interventional cardiologist and an associate professor of internal medicine at the University of Michigan Health System. [Beyond Vegetables and Exercise: 5 Surprising Ways to Be Heart Healthy]
"If you start to get some chest pain and indigestion that doesn't want to go away, please get it checked out," Gurm said.
In the study, Gurm and his colleagues tallied the number of hospital admissions for heart attacks in Michigan from Jan. 1, 2010, and Sept. 15, 2013, using a large insurance database. There were more than 42,000 heart attacks during the study period, and the researchers compared the daily totals around the start or stop of daylight saving time with the totals on other days during the study period.
Aside from the increase in heart attacks after people lost an hour of sleep, the researchers also found that on the Tuesday following the end of daylight savingtime in the autumn, when people gained an hour of sleep, heart attack numbers fell by 21 percent.
"If you look at the fall, there's a slight decline," Gurm said. "I think all of us need to get some more sleep."
But the researchers noted that when they looked at the numbers of heart attacks on a weekly basis, instead of daily totals, the number of heart attacks during the week before and after the time changes stayed pretty much the same as other weeks examined in the study. This suggests that spring daylight saving may have affected people who were going to have heart attacks anyway, Gurm said.
"It's something that has also been seen with other stressors," such as tsunamis or earthquakes, Gurm told Live Science. "It seems like people who are more prone to get heart attacks, their heart attacks may be more precipitated by the stress," he said.
Dr. Suzanne Steinbaum, a preventive cardiologist at Lenox Hill Hospital in New York City, who was not involved in the study, agreed that people may benefit if they pay extra attention to their heart health after daylight saving starts.
"For those people at risk for heart disease, it is important to try to get to bed a bit earlier the night before, and consider starting that pattern several days before the change is going to happen," Steinbaum said. "It is important to get enough sleep, so staying away from caffeine later in the day, and not engaging in exercise or stimulating activities towards the end of the day may help."
The exact reasons for the rise of heart attacks in the spring aren't clear, but researchers have several ideas. The hour change may disrupt circadian rhythms and interfere with cortisol levels, hormones that fluctuate throughout the day to help manage stress on the body, and increase blood sugar when sugar levels are low.
Moreover, "Mondays traditionally have been shown to be a day with a higher rate of heart attacks," and the change in time may only add to the heart attack risk, Steinbaum said.
"The good news is after Monday, the increased risk of heart attacks decreases," Steinbaum said. "Your body will quickly adjust to the change and loss of an hour of sleep."